Micromagnetic simulation for the effects of core-shell distributions of RE on the magnetic properties of dual-main-phase Nd-Fe-B based magnets

作者：Li, Wei; Zhao, Lizhong; Liu, Zhongwu^*

来源：Journal of Magnetism and Magnetic Materials, 2019, 476: 302-310.

DOI：10.1016/j.jmmm.2018.12.107

• Dual-main-phase magnets
• Core-shell distributions of RE
• Micromagnetic simulation
• RE diffusion
• Coercivity

Inspired by the experimental discovery, the effects of core-shell distributions of RE on the properties of the dual-main-phase rare earth-iron-boron (RE-Fe-B) magnets are investigated by micromagnetic simulation. In the dual-main-phase (DMP) magnets containing two main phases of hard magnetic Ce-free and Ce-rich RE2Fe14B, the nucleation tends to occur in the Ce-rich RE2Fe14B grains due to their low anisotropy field. The coercivity of dual-main-phase magnets without core-shell distributions of RE is much lower than that of the single-main-phase (SMP) magnets with the same nominal composition, though the Ce-rich RE2Fe14B grains are dipolar coupled by the Ce-free RE2Fe14B grains. The formation of core-shell distributions of RE main phase in DMP magnets adjusts their magnetic behavior. The appearance of the Nd-rich shells in the Ce-rich RE2Fe14B phases due to Nd diffusion will retard the nucleation of reversal domain because of the increased anisotropy field of the grain surface. The demagnetizing field of the Nd2Fe14B phases is also decreased by the shell structure, which further reduces the possibility of the nucleation. On the other hand, the formation of the shells by Ce diffusion in the Nd2Fe14B phase will promote the nucleation of reversal domain due to the reduced surface anisotropy field. It can increase the demagnetizing field of the Ce-rich RE2Fe14B phases and therefore increase the possibility of the nucleation. Hence, good magnetic properties can be only obtained in the DMP magnets with more Nd diffusion and less Ce diffusion, which is consistent with the experimental results.

• 出版日期2019-4-15
• 单位华南理工大学